By Ariane de Vogue, CNN Supreme Court Reporter
(CNN) -- The Supreme Court said Monday that unanimous jury verdicts are required in state criminal trials for serious offenses, handing a victory to criminal defendants including petitioner Evangelisto Ramos, who was convicted of murder in Louisiana on a 10-2 vote.
Ramos argued that Louisiana's non-unanimous jury provision violated his federal constitutional right to trial by jury and that the law had racist roots meant to diminish the votes of minority jurors.
Justice Neil Gorsuch penned the opinion and was joined in key parts by Justices Ruth Bader Ginsburg, Sonia Sotomayor, Stephen Breyer and Brett Kavanaugh.
"We took this case to decide whether the Sixth Amendment right to a jury trial -- as incorporated against the States by way of the Fourteenth Amendment -- requires a unanimous verdict to convict a defendant of a serious offense," Gorsuch wrote.
"One of these requirements was unanimity," he said, "a jury must reach a unanimous verdict in order to convict."
"The answer is unmistakable," he said.
Justice Clarence Thomas concurred in the judgment on narrower grounds, whereas Chief Justice John Roberts and Justice Elena Kagan joined Justice Samuel Alito's dissent.
In general, over time, the Supreme Court has ruled that most of the Bill of Rights applies not only to the federal government but to the states. But in 1972, the court held that while the Sixth Amendment requires unanimous jury verdicts for federal criminal trials, such verdicts are not required for state trials. Only two states allowed non-unanimous jury verdicts in criminal cases, Oregon and Louisiana, and Louisiana changed its law effective January 1, 2019.
Gorsuch said that while the two states continued to allow non-unanimous verdicts, their practices have "always stood on shaky ground."
In ruling in favor of Ramos, the court overturned the 1972 case, triggering a heated debate among some of the justices that might foreshadow future cases to come concerning issues that often closely divide them.
Kavanaugh wrote separately to explain why the prior case, called Apodaca, should be overruled. He said that while the notion of "stare decisis" -- a legal term that means to "stand by that which has been decided" is important court doctrine, there are times when the court should "overrule erroneous precedents."
He said that when the court overrules precedent, it demands a "special justification or strong grounds." He went on to list factors the court should consider including whether a prior decision was "egregiously wrong" and whether it has caused "significant negative jurisprudential or real-world consequences."
Writing the main dissent, Justice Samuel Alito, joined by the Chief Justice and in part by Kagan, said that "stare decisis" gets "rough treatment in today's decision."
He said the Apodaca case should be retained in part because Louisiana and Oregon had relied upon it for 48 years and "conducted thousands and thousands of trials under rules allowing non-unanimous verdicts."
"Now, those States face a potential tsunami of litigation," he said as defendants whose cases are still active will presumably be entitled to a new trial if they were convicted by a less-than-unanimous verdict.
In 2014, Ramos was convicted by a 10-2 vote of the second-degree murder of Trinece Fedison after her body was found in a trash can in a wooded area in New Orleans.
Ramos argued that Louisiana's law that permitted non-unanimous jury verdicts in non-capital cases violated his federal constitutional rights. He also said that Louisiana's rule -- embedded in the state's constitution since 1898 -- has racist roots as it was adopted to enable white majorities to outvote black minorities in the jury box.
"As the Court has said many times over many decades, the Sixth Amendment requires a unanimous verdict to convict," Jeffrey Fisher, a lawyer for Ramos told the justices. He said that the opinion, in Louisiana, would only impact about 36 cases that are on direct review.
Louisiana countered that the Sixth Amendment's right to a jury trial does not require criminal convictions by a unanimous jury in state or federal courts. In court, a lawyer for Louisiana argued that if the Supreme Court were to rule in favor of Ramos the ruling could apply to some 32,000 people that are currently serving time for serious crimes because thousands of petitioners would come to the court demanding relief. Oregon filed a friend of the court brief arguing that if the court were to rule in favor of Ramos it would require the retrial of "hundreds if not thousands of cases."
This story has been updated with additional information about the case.